JP2011203157A - Dial lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dial lighting system for reliably improving visibility of a dial.SOLUTION: The dial lighting system includes a light guide plate 200 comprising a plate-like light guide provided with a light incident part 203, and an emitter 300 for making light incident on the inside of the light guide plate from the light incident part. The dial lighting system 100 radiated on the front of the light guide plate by being irregularly reflected with an irregular reflector 205 provided on the backside of the light guide plate by light incident on the inside of the light guide plate has an index 200a molded by printing on the front side of the light guide plate. The index overlaps and prints different kinds of ink and has a first ink layer 200a(1) and a second ink layer 200a(2) in order from a light guide plate side. The ink of the first ink layer is far superior in reflection of light than the ink of the second ink layer.

Description

  The present invention relates to an apparatus for illuminating a dial such as a timepiece.

  In general, there is known a dial illuminating device including a light guide plate made of a plate-shaped light guide provided with a light incident portion, and light emitting means for making light incident on the inside of the light guide plate from the light incident portion. The light incident on the inside of the light guide plate is diffusely reflected by the irregular reflection means provided on the back surface of the light guide plate and radiated to the front surface of the light guide plate. An indicator is provided on the light guide plate, which is used as a dial. Alternatively, a translucent plate body provided with an index is provided in front of the light guide plate, and the plate body is a dial. Patent Documents 1 to 3 disclose a timepiece using a dial illuminating device of this type as a timepiece having a night display function.

JP 2009-216629 A JP 2009-216630 A JP 2009-229360 A

  Now, there are various possible configurations for the indicator provided on the dial. When the light guide plate is used as described above, the indicator is printed on the front surface of the light guide plate, or is formed on the front surface of the light guide plate. The structure which arrange | positions the transparent or semi-transparent plate body which printed this is considered. According to printing the colored ink and forming the indicator, the indicator is visually recognized by the color of the ink in a bright place. Also, it appears as a black shadow in dark places.

  In dark places, it is advantageous that the contrast between the indicator and its surroundings is clear. Here, when considering a structure in which light is irregularly reflected by the irregular reflection means and emitted to the front surface of the light guide plate, it is understood that the index that rises as a black shadow causes light loss. As a specific phenomenon, the ink absorbs light.

  The index occupies a certain area in front of the light guide plate, and the light loss increases as the area increases. In order to fully utilize the light of the light emitting means, it is considered that a structural device for dealing with such light loss is necessary.

  This invention is made | formed in view of this situation, The objective is to provide the dial illuminating device which improves the visibility of a dial reliably.

  The invention described in claim 1 of the present application includes a light guide plate made of a plate-shaped light guide provided with a light incident portion, and a light emitting means for making light enter the light guide plate from the light incident portion, In the dial illuminating device in which the light incident on the inside of the light guide plate is diffusely reflected by the irregular reflection means provided on the back surface of the light guide plate and radiated to the front surface of the light guide plate, on the front side of the light guide plate, An index formed by printing, and the index is formed by overprinting different types of ink, and includes a first ink layer and a second ink layer in order from the light guide plate side, and the first ink The ink of the layer is a dial illuminating device having a configuration in which light is more reflective than the ink of the second ink layer.

  The invention described in claim 2 of the present application is the dial illuminating device according to claim 1, wherein the edge of the second ink layer is surrounded by the edge of the first ink layer.

  ADVANTAGE OF THE INVENTION According to this invention, the dial illuminating device which improves the visibility of a dial reliably can be obtained.

It is a side sectional view of a timepiece provided with a dial illuminating device concerning an example of the present invention. It is a front view which concerns on the Example of this invention and shows a light-guide plate. It is explanatory drawing which concerns on the Example of this invention and shows a light-guide plate. It is explanatory drawing which concerns on the Example of this invention and shows a light-guide plate. It is explanatory drawing which concerns on the Example of this invention and shows a light emission means and a protrusion. It is explanatory drawing which concerns on the Example of this invention and shows a light emission means and a protrusion. It is an exploded perspective view showing a dial illuminating device (thing which printed and indicated a marker on a light guide plate) concerning an example of the present invention. It is explanatory drawing which concerns on the Example of this invention and shows the 1st ink layer and 2nd ink layer of a parameter | index. It is explanatory drawing which shows the principal part (1st ink layer) of a parameter | index concerning the Example of this invention. It is explanatory drawing which shows the principal part (a 1st ink layer and a 2nd ink layer) of a parameter | index in the Example of this invention. It is a disassembled perspective view which shows the dial plate illuminating device (thing which printed and shape | molded the parameter | index on the plate body) concerning the Example of this invention. It is explanatory drawing of the course of light in connection with the Example of this invention, (A) is a case where only a light-guide plate and a 1st sheet body, (B) is the case where a translucent plate body is provided in the front of a light-guide plate (C) has shown the case where the 2nd sheet body which diffuses light is provided in the front of a light guide plate, and the plate body is provided in the front of the 2nd sheet body.

  Embodiments of the present invention will be described below with reference to FIGS. A timepiece 1 shown in FIG. 1 is an analog radio-controlled timepiece that receives a standard time radio wave and automatically corrects the display time. The timepiece 1 includes a control means (not shown) that stores a required program for controlling the timepiece device 1, a dial illuminating device 100 that illuminates the dial, and a pointer 11 disposed in front of the dial. , 12 and 13, a movement 20 for rotating the hands 11, 12 and 13, and a housing 30 for storing them. The dial plate is formed by providing an index 200 a on a light guide plate 200 described later, and is covered with a transparent cover 31 supported on the front surface of the housing 30. 40 in the figure is an antenna for receiving standard time radio waves.

  As a pointer, an hour hand 11, a minute hand 12, and a second hand 13 are provided. The movement 20 is provided on the back portion of the light guide plate 200 and is configured to rotate the hands 11, 12, and 13 at a predetermined speed via a needle pipe 21 protruding to the front side of the light guide plate 200. . In the center of the light guide plate 200, a through hole 201 that penetrates the pointer pipe 21 is provided. In addition, as positioning means for positioning the light guide plate 200 in the housing 30, a boss 32 and a hole 202 into which the boss 32 is fitted are provided at essential portions of the light guide plate 200 and the housing 30.

  The dial plate illumination device 100 of this example includes a light guide plate 200 made of a plate-shaped light guide provided with a light incident portion 203, and a light emitting means 300 that makes light enter the light guide plate 200 from the light incident portion 203. The light incident on the inside of the light guide plate 200 is diffusely reflected by the irregular reflection means provided on the back surface of the light guide plate 200 and radiated to the front surface of the light guide plate 200. Further, a white first sheet body 210 is provided on the back surface of the light guide plate 200 so as to cover the entire portion where the irregular reflection means is provided. The first sheet body 210 prevents light leakage to the back side of the light guide plate 200. The indicator 200 a is provided on the front surface of the light guide plate 200.

  As shown in FIGS. 2 and 3, the light guide plate 200 is circular or substantially circular (polygonal, elliptical, etc.), and the edges of the light guide plate 200 are equally spaced in the circumferential direction. A plurality of projecting pieces 204 are provided. In the illustrated example, three projecting pieces 204 are provided at intervals of 120 ° with respect to the center of the light guide plate 200. The light emitting means 300 is disposed for each of the plurality of projecting pieces 204.

  An optical sensor 50 for detecting the brightness of the environment is provided on the back of the light guide plate 200, and the control means turns on the light emitting means 300 when the environment becomes dark, and turns it off when the environment becomes bright. For example, when the room is turned off at night, the light emitting means 300 is turned on and the light guide plate 200 is illuminated. The light emitting means 300 is turned off when the sun rises and becomes brighter.

  The irregular reflection means of this example is one in which convex reflection dots 205 are distributed on the back surface of the light guide plate 200. The reflective dots 205 are spherical, conical, pyramid, prismatic, or cylindrical fine convex portions that are formed integrally with the light guide plate 200 by injection molding.

  In the case of this example, the reflective dots 205 are distributed over substantially the entire back surface of the light guide plate 200. The area occupied by the reflective dots 205 is set to be sparse in a portion where the reflective dots 205 are distributed and the light that is irregularly reflected is relatively strong, and the area occupied by the reflective dots 205 in a portion where the light that is irregularly reflected is relatively weak. Is set densely. Basically, the area occupied by the reflective dots 205 is sparse at a portion close to the light emitting means 300 in consideration of the directivity characteristics of the light emitting means 300 and gradually becomes denser as the distance from the light emitting means 300 increases. With this configuration, the light emitted to the front surface of the light guide plate 200 is made uniform. The black portion in FIG. 2 indicates a portion where the reflective dots 205 are distributed, and the density represents the density of the area occupied by the reflective dots 205 (thin portions are sparse and dark portions are dense).

  Specifically, the reflective dot 205 is set to be small at a site where the reflective dots 205 are distributed and the light that is diffusely reflected is relatively strong, and the reflective dot 205 is set to be large at a site where the light that is diffusely reflected is relatively weak. ing. That is, the distribution interval of the reflective dots 205 is constant, and the size of the reflective dots 205 is set according to the light intensity inside the light guide plate 200.

  Alternatively, as shown in FIG. 4, the interval between the reflective dots 205 is set wide at a portion where the reflective dots 205 are distributed and the light that is irregularly reflected is relatively strong, and at the portion where the light that is irregularly reflected is relatively weak. The interval between the reflective dots 205 may be set narrow. That is, the size of the reflective dots 205 may be constant, and the interval between the reflective dots 205 may be set according to the intensity of light inside the light guide plate 200.

  In any case, the ratio per unit area occupied by the reflective dots 205 in the portion where the reflective dots 205 are distributed is in the range of 23 to 77%. In addition, the diameter of the reflective dot 205 with respect to the planar direction of the light guide plate 200 may be set in the range of 1.0 to 0.2 mm in consideration of the light reflection function, the formability of the reflective dot 205, and the like. According to such a configuration, the brightness of the dial can be made extremely rational. The concept will be described below.

  The light guide plate 200 emits light from a portion provided with irregular reflection means on the back surface. Here, when the entire dial is caused to emit light, the irregular reflection means is provided on the entire back surface of the light guide plate 200. There are various methods for providing the irregular reflection means, but usually a graining process such as a sandblasting process or an etching process is performed.

  Problems when light is emitted from the entire dial plate include that the part far from the light emitting means 300 becomes dark, and that the brightness varies greatly depending on the angle at which the dial is viewed. Such a problem is particularly noticeable when the dial is enlarged. For example, a small watch such as a wristwatch can be dealt with by adjusting the amount of light emitted from the light emitting means 300. However, when the watch is a large watch such as a wall clock, the brightness unbalance is clear. Will appear.

  First, according to the conventional texture processing, it is impossible or difficult to make light emitted to the front surface of the light guide plate 200 uniform throughout the light guide plate 200. This is because, in the light guide 200, what is important is to have a total reflection surface for guiding light far in the light guide 200 and a diffuse reflection surface for irregularly reflecting light. This is because the distribution of the total reflection surface and the irregular reflection surface must be set as appropriate in accordance with the size and shape of the light guide plate 200 in order to make the emitted light uniform. When the graining process such as the sandblasting process or the etching process is performed, the flat total reflection surface is almost lost, so that the part near the light emitting means 300 is bright and the part far away is dark.

  In view of this, the present inventor has considered the relationship between the total reflection surface and the irregular reflection surface, and has proposed a configuration in which convex reflection dots 205 are distributed on the back surface of the light guide plate 200. A space between the reflective dots 205 and the reflective dots 205 is a total reflection surface. In order to make the light emitted to the front surface of the light guide plate 200 uniform, the density of the area occupied by the reflective dots 205 is set according to the intensity of the light irregularly reflected by the reflective dots 205.

  The intensity of light irregularly reflected by the reflective dots 205 includes the distance from the light emitting means 300, the directivity of the light emitting means 300 to be used, the shape of the light guide plate 200, the position and shape of the light incident portion 203, the distribution state of the reflective dots 205, and the like. Depends on. The distribution of the reflective dots 205 is designed so as to approach an ideal state in which the light emitted to the front surface of the light guide plate 200 is uniform in consideration of these. That is, the area occupied by the reflective dots 205 is set sparsely in a portion where the reflective dots 205 are distributed and the light that is diffusely reflected is relatively strong, and the area occupied by the reflective dots 205 in a portion where the light that is diffusely reflected is relatively weak Will be set densely. According to such a configuration, the brightness of the dial can be made uniform.

  As shown in FIG. 5, the light incident portion 203 is formed by forming the tip end surface of the protruding piece 204 into a concave shape. The light emitting means 300 is a light emitting diode mounted on the substrate 301. Supporting portions for supporting the substrate 301 are provided on both sides of the light incident portion 203, and the substrate 301 is configured to be supported by the projecting piece 204 so as to cover the light incident portion 203. The support part shown in FIG. 5 is a groove part 204 a for inserting the substrate 301. Further, the substrate 301 inserted into the groove portion 204a may be prevented from being detached by attaching an adhesive tape from the front side and the back side of the light guide plate 200. By making the adhesive surface of the adhesive tape a silver-colored glossy surface and covering the light emitting means 300 and the light incident part 203 from the front side and the back side of the light guide plate 200 with the adhesive tape, the light incident part 203 is incident. Loss of light can be reduced.

  Alternatively, as shown in FIG. 6, the support portion may be an adhesive surface 204 b that adheres the substrate 301. The structure in which the light emitting means 300 is supported on the protruding piece 204 in this way is an extremely advantageous structure in that the brightness of the dial is made uniform. The concept will be described below.

  Conventionally, this type of dial plate illumination device 100 is configured to support the light guide plate 200 and the light emitting means 300 with respect to the housing 30. The light emitting means 300 needs to be installed at a predetermined interval and a predetermined angle with respect to the light incident portion 203 of the light guide plate 200 due to its directivity. As a result of repeating trial manufacture and examination, the inventor of the present application pays attention to the fact that it is extremely difficult to ensure the positioning accuracy when arranging a plurality of light emitting means 300 for one light guide plate 200. Was invented.

  That is, when the light guide plate 200 and the light emitting means 300 are respectively supported with respect to the casing 30, the positional relationship between the light emitting means 300 and the light incident portion 203 is determined by positioning errors and dimensions of the light guide plate 200 and the light emitting means 300 relative to the casing 30. Affected by error. Accumulation of each error is also a problem. If there is only one light emitting means 300, it can be dealt with to some extent by fine adjustment at the time of assembling them, but if there are a plurality of light emitting means 300, the light guide plate 200 is moved relative to the specific light emitting means 300. It cannot be fine tuned.

  Therefore, the light emitting unit 300 is supported by the protruding piece 204 without being supported by the housing 30. According to such a configuration, the positional relationship between each light emitting means 300 and each light incident portion 203 can be ensured accurately, and the brightness of the light guide plate 200 can be made more uniform.

  Next, the index 200a of this example will be described. As shown in FIGS. 7 to 10, the dial illuminating device 1 includes an indicator 200 a formed by printing on the front side of the light guide plate 200.

The index 200a is obtained by overprinting different types of ink on the front surface of the light guide 200, and the first ink layer 200a (1) and the second ink layer 200a (in order from the light guide plate 200 side). 2). The ink of the first ink layer 200a (1) is more excellent in light reflectivity than the ink of the second ink layer 200a (2). The indicator 200a is formed by printing the first ink layer 200a (1) on the front surface of the light guide plate 200 (see FIG. 9), and then forming the second ink on the first ink layer 200a (1). The layer 200a (2) is provided by printing (see FIG. 10). Further, the edge of the second ink layer 200a (2) is surrounded by the edge of the first ink layer 200a (1). The distance between the edge of the second ink layer 200a (2) and the edge of the first ink layer 200a (1) is 0.1 mm to 1.0 mm.
The indicator 200a is visually recognized by the color of the second ink layer 200a (2) in a bright place. Also, it appears as a black shadow in dark places. According to such a configuration, it is possible to improve the visibility of the dial very reasonably. The concept will be described below.

  First, the ink of the second ink layer 200a (2) is set in consideration of the color in a bright place. However, since it is a colored ink that preferentially adopts color, if the index 200a is composed only of this ink, it is considered that the loss of light caused by the ink absorbing light is large when illuminated in a dark place. . In this regard, the first ink layer 200a (1) reflects light by providing the first ink layer 200a (1) made of ink having excellent light reflectivity as in this example on the light guide plate 200 side. As a result, light loss is reliably reduced.

  The inventor of the present application made a prototype of the first ink layer 200a (1) and the one without the first ink layer 200a (1), and compared the visibility of both. As a result, it was confirmed that in the case where the first ink layer 200a (1) was provided, the brightness and darkness between the index 200a and its surroundings became relatively clear, and the light loss was reduced. The ink of the first ink layer 200a (1) is not particularly limited, but a white glossy ink is desirable.

  If the edge of the second ink layer 200a (2) is surrounded by the edge of the first ink layer 200a (1), the outline of the index 200a becomes clearer when illuminated in a dark place. There is an advantage of becoming. If the edge portion of the second ink layer 200a (2) protrudes from the edge portion of the first ink layer 200a (1), the protruding portion is lightly brightened by the light from the light guide plate 200. Thus, in this example, such a problem is avoided. As an ideal configuration, it is preferable that the edge of the first ink layer 200a (1) and the edge of the second ink layer 200a (2) are exactly the same. However, in overprinting, since a slight positional deviation occurs as a technical error, the first ink layer 200a (1) is set slightly larger than the second ink layer 200a.

  As described above, the dial illuminating device of this example is extremely rationally configured in terms of improving the visibility of the dial. In addition, it is needless to say that the configuration of each part in the present example can be appropriately changed in design within the technical scope described in the claims, and is not limited to that illustrated in the drawings.

  Next, another embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 11, the dial illuminating device 100 of the present example includes a second sheet body 220 that diffuses light in front of the light guide plate 200, and a transparent or translucent plate body in front of the second sheet body 220. 230 is provided. An indicator 200a is provided on the front side surface or the back side surface of the plate body 230, which serves as a dial. When the index 200a is provided on the front surface of the plate body 230, the first ink layer 200a (1) is printed and provided, and then the second ink layer 200a (1) is formed on the first ink layer 200a (1). 2) is provided by printing. When the indicator 200a is provided on the front side surface, the second ink layer 200a (2) is printed and then the first ink layer 200a (1) is printed on the second ink layer 200a (2). Provide. As the plate body 230, a milky white resin plate having a light transmittance of 55 to 65% is adopted. As the second sheet body 220, a synthetic paper mainly made of polypropylene is employed. Other configurations are the same as those in the above-described embodiment. According to the dial illuminating device 100 of this example, the brightness of the dial can be reliably improved. The concept will be described below.

  First, light is diffusely reflected by the irregular reflection means and emitted to the front surface of the light guide plate 200. Here, because of the property that light travels straight, if the irregular reflection means does not have directionality with respect to the light emitting means 300 as in this example, the amount of light emitted to the opposite side of the light emitting means 300 is inevitably required. (See FIG. 12A). Therefore, in the case where the light guide plate 200 is provided with the indicator 200a and used as a dial plate, the dial plate tends to appear brighter when viewed from the diagonally front side opposite to the light emitting means 300 than when viewed from the front. . Such a problem is alleviated when a translucent plate body 230 is provided in front of the light guide plate 200 (see FIG. 12B). That is, the configuration in which the translucent plate body 230 is provided is very effective as a practical configuration. Further, when the second sheet body 220 is disposed between the light guide plate 200 and the plate body 230, the effect becomes remarkable, and the brightness of the dial is almost the same when viewed from any angle (FIG. 12C). reference). That is, according to the configuration of this example, it is possible to reduce light unevenness and to ensure sufficient brightness when viewed from the front. This is also advantageous in that the power consumption of the light emitting means 300 is reduced.

  The dial plate illumination device of the present invention can be suitably used as a device for illuminating a dial of a wall clock or a table clock.

DESCRIPTION OF SYMBOLS 1 Clock 11 Hour hand 12 Minute hand 13 Second hand 20 Movement 21 Pointer pipe 30 Housing 31 Transparent cover 32 Boss 40 Antenna 50 Optical sensor 100 Dial plate illumination device 200 Light guide plate 200a Index 200a (1) First ink layer 200a (2) Second Ink layer 201 Through hole 202 Hole portion 203 Light incident portion 204 Projection piece 204a Groove portion 204b Adhesive surface 205 Reflective dot 210 First sheet body 220 Second sheet body 230 Plate body 300 Light emitting means 301 Substrate

Claims (2)

A light guide plate made of a plate-shaped light guide provided with a light incident portion; and a light emitting means for entering light into the light guide plate from the light incident portion, and the light incident on the light guide plate In the dial plate illuminating device diffusely reflected by the irregular reflection means provided on the back surface of the light guide plate and radiated to the front surface of the light guide plate,
On the front side of the light guide plate, an indicator formed by printing,
The indicator is formed by overprinting different types of ink, and includes a first ink layer and a second ink layer in order from the light guide plate side,
The dial illumination device according to claim 1, wherein the ink of the first ink layer is more excellent in light reflectivity than the ink of the second ink layer.   The dial illumination device according to claim 1, wherein an edge portion of the second ink layer is surrounded by an edge portion of the first ink layer.

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